Zoey The Bear

Hello guys, I am kinda new to the pool/hot tub industry, but I believe I'm catching on quick. I've been reading a lot of the posts here on this forum and found tons of answers and knowledge. However I've got something that is throwing me through loops and it's troublesome. I work at a local aquatic center and have been working with the chemical levels. This is mainly on the hot tub, but also I've noticed something similar going on with the pool. My issue is this... I come in first thing in the morning and find that the CAT controllers that we use read 6.9 pH and 750+ ORP. We use a combination of cal hypo and as a booster (when we have a huge bather load, sodium hypo for a sanitizer, and Acid Magic as the acid. The cal hypo is fed via the Accu-tab corrosion feeder, and our acid is fed through an adjustable speed (variable cam) Stenner Pump. I always double check to make sure that the chemical readings are correct by using a Taylor K-2006C Test Kit Complete Chlorine FAS-DPD. The readings are dead on. Now, the tricky part. I've watched the CAT controller over a period of 2 minutes. The pH can jump .1-.6 points!! I've tried adjusting the feed rate from high to low, but no results. This is without any addition of acid, unless of course it goes above the set point (7.5). The ORP is also jumping 20-60 points. I add sodium bicarb to get the levels within range. Any ideas what on what is going on?